In his first foray into the general election campaign, former Huntingdon MP Sir John Major has spoken out against the threat of a Labour-SNP pact to secure power, saying it will lead to economic disaster, higher taxes and job losses.

Shadow chancellor Ed Balls and shadow health secretary Andrew Burnham have suggested that Ed Miliband may be willing to do a post-election deal with SNP leader Nicola Sturgeon.

In a speech in the marginal seat of Solihull in the West Midlands on Tuesday, Sir John said: “This is a recipe for mayhem. At the very moment our country needs a strong and stable government, we risk an unstable one.

“It would put us on a course to a government held to ransom on a vote-by-vote basis.”

The ex-Prime Minister expressed concerns that the SNP joining forces with Labour would push politics further to the left and that the Scottish independence party’s main agenda would be to encourage the break up of the union.

“Let me not mince my words: the SNP is a real and present danger to our future. They will pit Scotland against England. That could be disastrous to the people of Scotland − and fatal to the UK as a whole.”